Nurseries and greenhouses regularly employ workers to reposition plants such as shrubs and trees in containers on plots of land as large as thirty acres or more. Numerous, for example hundreds or even thousands of containers may be brought to a field and then manually placed in rows at a designated spacing. Periodically, the containers are respaced, typically as the plants grow. Other operations include jamming, (e.g., for plant retrieval in the fall), consolidation, and collection. See U.S. Patent Application No. 2005/0135912 incorporated herein by this reference.
The use of manual labor to accomplish these tasks is both costly and time consuming. But, attempts at automating such container handling tasks have met with limited success.
Large-scale or hard automation is practiced at some greenhouses especially in Europe. The “Walking Plant System” (WPS Horti System, BV) is one prominent greenhouse automation scheme. In this method, conveyor belts, tables on tracks, and other centrally controlled mechanisms maneuver containers throughout the entire production cycle—plants are never placed on an outdoor floor or on un-actuated surfaces. Thus, from seed to sale, virtually no direct human labor is needed.
Such hard automation methods can be cost effective where land and labor prices are high and in operations where only one variety of plant is produced. But, in other circumstances (more typical of the U.S.), this form of automation loses some of its advantage. Because the automation components are fully integrated into the greenhouse, hard automation installations cannot easily be scaled up or down in response to demand. Further, the initial costs of a hard automation system is very high—growers essentially purchase a plant factory.
Visser International Trade and Engineering, BV has automated one container manipulation task known as “spacing.” Spacing involves positioning containers on an outdoor field or greenhouse floor with a surrounding buffer space so that plants have room to grow. A forklift-sized device called the “Space-O-Mat” uses multiple actuated forks to position plants in a regular pattern as the device backs up under autonomous control. The disadvantages of the Space-O-Mat become apparent when it is used on real-world field. If the surface is somewhat soft or uneven, the Space-O-Mat may fail to deposit containers properly. Also, many greenhouse are too tightly configured to accommodate Space-O-Mat.
A research project begun in 2000 and sponsored by NASA, Carnegie Mellon University, and the American Nurseries and Landscape Association developed a semi-autonomous device called Junior also intended to perform container spacing. Junior, a tractor-sized mechanism, automated part of the spacing task. Two workers move containers from a wagon to a conveyor on Junior that reaches across the wagon. The conveyor transports the plants to a mechanism with about a dozen grippers mounted on an arm. When each of the grippers has been loaded with a container, the arm activates. The arm maneuvers the plants onto the ground, spacing them relative to plants already on the ground. Then Junior backs up positioning itself to accept the next group of plants from the wagon.
Junior has not been developed into a commercial product. Were Junior to be offered for sale, it would likely have a high price. Junior is also a very complex piece of equipment and might require special expertise to operate. Because of its large size Junior cannot be used inside many greenhouses.